Meremelya, I. Y., and V. V. Savchuk. “Exact Constants in Inequalities for the Taylor Coefficients of Bounded Holomorphic Functions in a Polydisc”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 67, no. 12, Dec. 2015, pp. 1690-7, https://umj.imath.kiev.ua/index.php/umj/article/view/2101.